Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

188
FXUS63 KLOT 260445
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1045 PM CST Wed Feb 25 2026

.KEY MESSAGES...

- Quick burst of accumulating snow is possible overnight tonight
  mainly south of a roughly Streator to Remington line. Some
  locally slick travel conditions may develop.

- Brief warm for the end of the week, then colder with some
  additional snow chances over the weekend and into early next
  week.

&&

.UPDATE...
Issued at 815 PM CST Wed Feb 25 2026

Quick update this evening to locally boost snow chances tonight
mainly south of a La Salle to Rensselaer line and add some light
accumulations to the gridded forecast.

Regional water vapor loops reveal a mid-level impulse tracking
quickly eastward across central Iowa, more-or-less along a well
established 850-700 mb baroclinic zone. Modest confluent flow
ahead of the eastward-advancing disturbance in the vicinity of
this thermal gradient is resulting in increased 700 mb
frontogenesis which in turn is driving a fairly notable
vertical ageostrophic response across east central Iowa. Have
noted some ephemeral but respectable banding off the DMX/DVN
radars, and snow has become heavy enough in localized corridors
to punch through an preceding dry layer near the surface.

Going forward, the northern terminus of the main 700 mb f-gen
axis is forecast to push across our far southern locales later
this evening and into the early overnight hours, with some
guidance depicting a local intensification of the fgen
circulation as the associated impulse tracks overhead.
Additionally, regional cross sections through the sloping region
of f-gen reveals an increase in negative saturated EPV during
this period revealing the presence of at least some instability
for slantwise parcels. While surface dewpoint depressions are
currently running 20+ degrees, sufficient snow production aloft
may be enough to break through this dry layer. Boosted snow
chances into the high-end chance category, right up to likelies
south of a La Salle to Rensselaer line. Did not go higher than
that right now given the aforementioned dry subcloud layer, but
if upstream trends continue, will need to further increase PoPs
in this localized corridor across our far south. Additionally,
added some light snow accumulations in this region. Given the
fast-moving nature of the main disturbance, any accumulating
snow window will be pretty brief, perhaps 2-3 hours, and have
confined PoPs to the roughly 11 pm - 3 am time frame.

If fgen forcing remains pronounced into our region and dry air
erodes quickly, it wouldn`t be out of the question for banding
to overperform with a quick burst of 1-2" of snow in hyper-
localized corridors given the mentioned instability and fgen
profile. At this time, it`s unclear if that will be the case,
or if this occurs just south of our CWA. Incoming NAM/NAMNest
are a bit concerning in this regard (and seem to be handling
upstream activity okay), revealing a brief uptick in UVVs
nearing 15-20 ubar/sec in this region. Regardless, will trend
the snow forecast up a big in our far south and continue to
closely monitor upstream trends this evening.

Carlaw

&&

.DISCUSSION...
Issued at 121 PM CST Wed Feb 25 2026

Temperatures this afternoon remain in the 30s. Winds are out of
the northwest and slightly breezy with gusts around 20 mph.
Other than those chillier temperatures, it has been quite a
beautiful day. However, satellite imagery shows cloud cover
associated with an upper level trough over the northern Plains
that is dropping southeastward. In addition to an increase in
cloud cover across the region, this system will provide the next
chance for accumulating snow for central Illinois. Models
continue to keep the track of the surface low well to the south
of our area. The best chance for snow remain south of a Peru,
Illinois to Lafayette, Indiana line, but accumulations should be
less than an inch. A flurry north of that line cannot be
completely ruled out, but confidence remains low.

Surface high pressure will grow locally Thursday as an upper
level trough moves over central Canada Friday into Saturday.
Winds will turn southerly and usher in milder temperatures
tomorrow, with a chance for highs to touch the low 60s on
Friday (about 20 degrees above normal!). As the Canadian trough
strengthens on Friday, the pressure gradient response over the
region will tighten and allow for breezier conditions to develop
with wind gusts 25 to 30 mph expected.

A cold front associated with the Canadian trough will move over
the forecast area Friday night through Saturday morning. NBM
PoPs remain in the 20 to 40 percent range and given how far away
the area is from the better forcing, these PoPs seemed
reasonable. While there is a chance of snow, the lack of QPF
with this system and drier air near the surface trends toward
minimal accumulations, with the better chances north of
Interstate 88. As the baroclinic zone gets hung up over central
Illinois, a sharp temperature gradient is expected with mid to
upper 40s south of Interstate 80 and mid to upper 30s to the
north.

Persistent northwest flow behind the front will return chillier
temperatures to the area through early next week. Highs on
Sunday and Monday are expected in the 30s with morning lows in
the teens to mid 20s. Another synoptic system is expected to
drop out of Canada on Sunday and pass over Illinois Sunday night
into Monday. While this system does look like it could produce
accumulating snow, models are consistently trending the track
just south of our forecast area. There is still a lot of
discrepancies in the ensembles, but it looks like the best
chances for snow are south of Interstate 80.

The pattern next week looks somewhat active as models are trying
to resolve another upper level trough to pass over the area on
Tuesday and maybe another late in the week. With winds
potentially turning to the south on Tuesday, it would allow for
better warm air advection out ahead of it. This could lead to
chances for rain versus snow, but it is too early to say. But
the extended models do appear to be favoring a gradual warming
trend through the end of next week.

DK

&&

.AVIATION /06Z TAFS THROUGH 12Z FRIDAY/...
Issued at 1045 PM CST Wed Feb 25 2026

There are no forecast concerns this period. Light northwest
winds will become variable or calm overnight then become
south/southwest Thursday morning, increasing to 10-12kt in the
afternoon with some higher gusts possible. Low level winds will
increase Thursday evening and will need to be monitored for
possible low level wind shear. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

Visit us at weather.gov/chicago